Article révisé par les pairs
Résumé : The ISO has developed two Formal Description Techniques to describe precisely data communication protocols. One of these namely ESTELLE, has been used to specify a subset of the Network Independent File Transfer Protocol, also called Blue Book, promoted by the Joint Network Team in the United Kingdom. An implementation in the C programming language is currently being derived from this partial specification. Some difficulties have been encountered during both the process of building the specification and the process of building the corresponding implementation. They are listed and explained. Some of them are suprisingly not due to the problem but result from the use of the solving tool! © 1988.